In recent years, various devices which print a corrugated fiberboard using an inkjet type printing device have been developed. In the inkjet type printing device, there is a concern that an inkjet head is damaged if the corrugated fiberboard comes into contact with an inkjet head, and it is necessary to maintain a distance between the inkjet head and the printing surface of the corrugated fiberboard to an appropriate range in order to maintain a constant printing quality. However, since the corrugated fiberboard is not fully flat and is bent or corrugated, in the corrugated fiberboard, a location which slightly floats from a sheet transport passage is generated.
In a case where the inkjet type printing device is applied to the printing of the corrugated fiberboard, it is necessary to prevent the distance between the corrugated fiberboard and the inkjet head from being deviated from an appropriate range (including a contact between the corrugated fiberboard and the inkjet head) due to the floating.
For example, as a technology which maintains the distance between the printing surface of the corrugated fiberboard and the inkjet head to an appropriate range, there is a technology which is disclosed in PTL 1. Hereinafter, the technology which is described in PTL 1 is explained. For reference, reference numerals used in PTL 1 are indicated in parentheses.
A box-making machine (1) of a corrugated fiberboard disclosed in PTL 1 (refer to paragraphs [0021] to [0023 and FIGS. 1 to 6] includes an inkjet type ink head (30) which injects liquid ink to a corrugated fiberboard (S) and a sheet guide device (46) for maintaining a printing quality so as to hold a gap value between the ink head (30) and the corrugated fiberboard (S) to an optimal gap value (t).
The sheet guide device (46) includes a sheet guide (47) which comes into surface contact with the corrugated fiberboard (S) on at least one of the upstream side and the downstream side of the ink head (30) to reduce micro vibrations of the corrugated fiberboard (S). Preferably, the sheet guide (47) is not only displaced on the corrugated fiberboard (S) simply so as to stabilize the corrugated fiberboard (S) when the printing is performed, but the sheet guide (47) is also slightly pressed to the corrugated fiberboard (S) so as to not substantially collapse the corrugated fiberboard (S).